This section introduces aspects that may be helpful to facilitate a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art. Any techniques or schemes described herein as existing or possible are presented as background for the present disclosure, but no admission is made thereby that these techniques and schemes were heretofore commercialized, or known to others besides the inventors.
Cavity resonators typically include a cavity enclosed by metal walls that confine electromagnetic fields, e.g. in the microwave region of the spectrum. The cavity may include a center electrode, sometimes referred to as a post. At a resonant frequency determined in part by the dimensions of the cavity, electromagnetic waves may resonate, forming standing waves in the cavity. Thus the cavity may act as a bandpass filter, allowing microwaves of a particular frequency to pass while blocking microwaves at other frequencies.